Curiosity rover detects spikes of methane at Mars

This Feb 3, 2013 image provided by NASA shows a self portrait of the Mars rover, Curiosity. NASA's Mars rover, Curiosity, has detected spikes of methane in the planet's atmosphere.

CAPE CANAVERAL, Fla. — NASA's Mars rover, Curiosity, has detected spikes of methane in the planet's atmosphere. That suggests something is producing or venting the scientifically tantalizing gas, but no one knows what.

Most of Earth's atmospheric methane comes from animal and plant life, and the environment itself. So the Martian methane raises the question of past or present microbial life. Or the gas elevations could come from geological sources, comet impacts or something else entirely.

The latest study, released Tuesday by the journal Science, indicates there's less than half the expected amount of methane in the atmosphere around Curiosity's location in Gale Crater. But over a full Martian year, the rover measured fairly frequent occurrences of elevated methane levels — tenfold increases.

The Jet Propulsion Laboratory's Christopher Webster led the international study.